A good publication for your professional library

Investigating Plants:
Hands-on, Low-cost Laboratory Exercises
in Plant Science
1996. 96 pages. ISBN: 0-941212-21-1.
National Association of Biology Teachers,
11250 Roger Bacon Drive, Reston, Virginia 20190.

An Inspiring Set of Activities
to Vivify Life-Science Classes

Ellen C. Weaver

Many biological principles can be elucidated through studies of plants -- remember Mendel and his peas! In most middle-school life-science books, however, the "activities" dealing with plants are minimal and may even be useless. Investigating Plants provides activities that help students to do real science and learn some meaningful biology, both by observing and by conducting experiments.

The booklet contains fourteen laboratory exercises -- "Flower Anatomy," "Seed Anatomy," "Seed Germination," "Germination & Environment," "Plant Growth & Anatomy," "Hormones & Asexual Reproduction," "Temperature," "Gravitropism," "Phototropism," "Respiration," "Chlorophyll," "Stomata & Photosynthesis," "Transpiration" and "Competition." The exercises were developed with the participation of a group of 7th-graders, and they are presented in a reasonable sequence that will help students to build their vocabularies as well as their knowledge of biology. However, each exercise is independent of the others. Teachers can pick and choose, or can alter the sequence, without sacrificing pedagogic effectiveness.

Little is required in the way of specialized equipment, and all the exercises are biologically sound.

Middle-school students who perform the activities described in Investigating Plants will learn to care for experimental organisms, will find that organisms don't always do what we expect them to do, and will see that experiments don't always produce the "right" results.

The writers of Investigating Plants recommend that students be permitted to use their own notebooks during quizzes -- a good idea that gives students a powerful incentive to keep orderly and complete records. As the writers put it:

Keeping journals and [keeping] good records are important in many activities, and they are essential in science. . . . Rather than ask students to memorize vocabulary and concepts that come from the exercises, we have them record this information in the notebooks. Open-notebook quizzes are a way to affirm the importance of good record keeping and to reinforce some of the ideas that may have been learned in an exercise.

Teachers who use Investigating Plants will have to know some basic botany (or will have to learn some by reading an introductory college text), and they will have to work around some minor defects in the descriptions of certain experiments. For example:

• In "Flower Anatomy" the writers cite only one plant, Gladiolus, whose flowers are appropriate for conducting the recommended observations. They should have named some alternatives, such as lilies, tulips or the garden pea. They also should have pointed out that some common plants, such as daisies or sunflowers or other composites, have flowers that are not suitable for use in this exercise.

• In "Germination & Environment" the writers don't explain that the "germination chamber" has been described in an earlier section.

• In "Hormones & Asexual Reproduction" the writers tell us that Coleus cuttings readily form roots, with or without any hormone treatment, and that "the effect of the hormone treatment for this particular species may be minimal." If that is true, why is Coleus being used here? Why not some other species, in which the effect of the hormone might be more pronounced?

• In "Temperature" the writers should have told that the light intensity must be the same at both temperatures. Otherwise, the results won't have any meaning.

• "Gravitropism" is hard to understand because it doesn't have enough illustrations. I wish that there were a diagram to help the teacher explain how a protractor can be used for measuring "the angle of root and shoot growth," as well as a diagram to show what the writers mean by an "outside row" of seeds.

• In "Respiration" the students are to discuss the question "Which would be better for you to eat -- corn or peanut?" This requires a value judgment that has little to do with the exercise. An appropriate question would be: "Which would be likely to provide more energy if it were used as food -- a gram of corn or a gram of peanut?"

• In "Stomata & Photosynthesis" the teacher needs to know the magnifications that are required for observing stomata and starch granules. The teacher would also find it helpful to know that stomata can be demonstrated in grocery-store plants, such as lettuce or spinach.

As I said, these deficiencies are minor. Overall, Investigating Plants is a good little book that can provide welcome inspiration to teachers of middle-school life science. I recommend it.

Ellen C. Weaver is a professor of biological sciences, emerita, from San Jose State University, a fellow of the American Association for the Advancement of Science, a past president of the Association for Women in Science, and a director of The Textbook League.

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